The HLT2AM Hi & Lo Shelving Analog EQ from Tube-Tech is a stereo unit combining variable high and low shelving EQ and filters with an adjustable midrange T-Filter. The shelving filters are designed around a high gain tube amplifier. The T-filter is a passive filter placed between the shelving filters and the output amplifier. All three sections are supplied with an in/out switch. The low and high cut filters are also passive with a slope of 6 dB/octave. A bypass switches the whole filter section out of the amplifier circuit, keeping the output stage in the circuit. This unit has stepped pots and a smaller and more detailed range for the shelf and T- filter EQ.

When the low end goes up, the high end goes down and vice versa. When the potentiometer is turned clockwise, the high frequencies are boosted and the low frequencies are attenuated. When the potentiometer is turned counter clockwise, the low frequencies are boosted and the high frequencies are attenuated. The unit is all tube based except for the power supply. Input and output have fully floating transformers. All DC voltages are stabilized, except the anode voltage for the output stage.